Pivoted leg instrument



Dec. l2, 1944. J. NASH PIVOTED LEG INSTRUMENT Filed May 17, 1945 llllf. i 1 ..1 Ew,

Patented Dec. 12, 19.44

PIVOTEDLEG INSTRUMENT James Nash, Sheboygan, Wis., assigner to William H. Murphy, executor of Harry De Lisle, deceased, doing business as Engineering Sale Company, Sheboygan, Wis.

Application May 17, 1943, serial No. 4s17,306

(c1. vca -156) 5 Claims.

The present invention relates to pivoted leg instruments of the class of which dividers, compasses and calipers may be considered as representative members. This invention may be considered as an improvement upon the device forming the subject matter of my copending patent application Serial No. 461,132, filed October 7, 1942, for Drafting instruments and the like.

Although the present invention is illustrated as embodied in a drafting or navigating compass, it will be appreciated that most of the novel features may to advantage be embodied in dividers, calipers or other pivoted leg instruments.

One of the objects of the present invention is` to provide a novel pivcted leg type instrument having the advantages' of the device forming the subject matter of the before mentioned cepending application and which in addition has simple means for quickly and easily aligning the tips at the free ends of the legs.

Another object of the present invention is to provide'a novel pivoted leg instrument formed principally of molded plastic pieces, which is economical to manufacture in large quantities, is neat in appearance, is easily and positively adjusted for transversemisalignment, which will remain set to a desired dimension, and which has a smooth soft action at the pivot, thus enablingl quick and easy adjustment of the tips to a desired setting.

Yet another object is to provide a novel compass having the above advantages, and further being adapted to have a lead chuck which does not require loosening and tightening a clamp'in order to move the lead inwardly or outwardly.

.Other objects and advantages will become apparent from the following description of a preferred embodiment of my invention illustrated in the accompanying drawing in which similar the lead 20 and tip I6 'to be brought together the point chuck.A This viewistaken along the line 5-5 of. Fig. llglooking downwardly as indicated by the arrows.

The principal elements of the pivoted leg instrument illustrated in the drawing are a pair of legs indicated by the numerals I0 and I2. These legs are pivoted at their upper ends, while their free lower ends may both be equipped with points to form dividers, or one leg I0 may have a chuck` I4 to receive a point I6, kwhile the other hasa lead chuck I8 to receive a pencil lead 2c to form` a compass. Inany event, I prefer that both legs be molded from a hard plastic substance, as an example, a phenol-formaldehyde condensation resin such'l as "Bakelite for instancebecause of manufacturing economies inherent in the use of such materials and because of theirlightness, re-l,

sistance to corrosion, and low specific heat which' prevents the instrument feeling cold to the touch. If desired, the legs may of course be formed Aof other materials. 1

A'cylindrical passage 22 extendsupwardly into the free end of the legfID, preferably slightly obliquely and is adapted to receive one end of the steel or other hard metal pointIS. The passage 22 is slightly oblique so that the lower tip* of the point IB can be set to aA position such that a line from the tip to the?. pivot will not pass through the leg portion I0. This,"together with a similar setting ofthe leadV chuck I8 enables without interference between the leg portions.

The point I6 is retained in position by a setscrewv 24 kthreaded transverselyinto the side of the leg. ina position such that it projects intoy the passage- 22.

characters of reference refer to similar parts throughout the several views.

Referring to the drawing: I `Figure 1 is a perspective view of a compass incorporating my invention; Y

Fig. 2 is a sectional view drawn to a larger scale, which may be considered as taken in the direction of the arrows substantially along the line 2 2 of Fig. 1;

Fig. 3 is a sectional view of the pivot mechanism taken in the direction of the arrows along The leg I2 cansimilarly be provided with a sharp point I6, or as shown, the end ofthe leg may have a metal sleeve 26 molded-in at thetime of forming, the sleeve being shaped and di.- mensioned to receive the` end of a mechanical pencil chuck, the'chuck shown being of the ltype used in Autopoint pencils manufactured by the Autopoint Company of 1801-West `Foster Avenue, Chicago, Illinois. Preferably the sleeve26 is set into the leg I2 'at a slightly oblique angle, asis the point I6, so that the lead 20 `and 'point I6 will come substantially together when the legs are closed. By properly` shaping the portion of the leg I2 immediately above the chuck I8, a pleasing appearance can 'be maintained evenl though theA chuck is somewhat more bulky than ordinarily used clamp type chucks. Although a clamp type chuck can be usedif desired, it is be# the legs l and l2 are in alignment.

As shown, the inner face 3i.y of. the disc 28 highly concave, its center being a matter of thou,- sandths of an inch or so below the edge- The sim--y ilar face 32 of the disc 23 is provided with two spherical knobs 34 spaced about. half the distance from the center to the edge of the disc. These knobs are arranged about 60 each side: of the. inner edge of the leer and in avposition above the. center of' the disc. In a similar position below its center, the disc 26 is threaded' to receive a short adjustment screw 3B' extending therethrough transversely, sov that the inner end of the4 screw 36 and' the knobs 34 are substantially equally spaced from each other andfrom the center of the face 32. The inner end of the screw 36 is cup pointed for a reason to be eX- plained presently.

The kdiscs 2.6. and 28 pivot about a cylindrical bushing 38 which. fits into. cylindrical recesses v411, counterbored or molded into the. faces 3|) andl 32., The bushing therefore. pre-vents. lateral shifting of the. two. legs. relative to.V each other,y but permits pivotal movement. A thin. washer 42 is4 located'around the. bushing, 3.3 in.. av position `be-y tween` the. faces. 3.8. and 32. This disc. bears with its, periphery against the concave face 3.0 and therefore. forms a. circular line. contact which gives a smooth pivotal movement. between thel disc: 23 and the, washer 42,. whileacting as av brake to. maintain any desired setting, of the. points.,

This circular line contact also prevents rocking of one leg relative to the other at the.

pivot point. The; washer 42 has a conical dent. formed in the.y face adjacent face 30, thus. forming a projection 44. on the opposite side, so lo'-` cated asy to fit into the cup pointof the adjustment screw 3.6. The adjustment screw therefore causes the washer 42. to rotate with leg I Il.

The. two le'gs are. clamped together by aV rivet` 4B which extends. centrally through the discs 28 and 26 in the order named and through the bushingj38. Between the rivet head and' the outer face of the disc 28 a thin washer 48 serves to reduce friction and prevents cutting of the 'face of the disc 28A by the inner surface of the rivet head'. The opposite end of the rivet extends through a, hole in the center-*of`r a star shaped spring 50, having its legs bearing against the outer face of disc 25, and is rolled overi to form a shoulder 52v to prevent separation of the spring from the rivet.

At the time theshoulder 52 isformed, the spring f 50 is slightly compressed; it therefore presses the faces 30 andI 32 againstr the washer 42? with an` between the concave facev 3G and; washer 42: pre;-` vents; wobbling and insuresr a smooth. pivoting action.` Further the. threev point contact-the knobs v34 and screw BE-between the leg I0 and against said washer.

tive rotation between these elements and thus prevents the possibility that the: end` ot the screw might cut a. groove iny the washer after extensive use of the instrument. d

Having described my invention in connection withV a preferred embodiment thereof, what I cla-im; as new and useful and desire to secure by Letters Patent4 is;

1.. A. pivoted; leg instrument comprising a pair oil legs: having similar circular disc-like contiguous faces: formed at their `upper ends, one of said faces being slightly concave, a hinge pin extending through and joining said legs in a position substantially .centrally of said faces, a thin flat Washer surrounding said pin and located between said faces and bearing against said concave face at its periphery, said washer being spaced from said concave face at points other than its periphery Iby reason of the concave nature of said face, the other of said faces having projections bearing against said washer, one ofV said projections being' adjustable to change the angle between the last said fac-e and said washer, and resilient means cooperating with said hinge pintending to urge said faces toward each other.

2. A pivoted leg instrument comprising a pair of legs having similar circular disc-like contiguthin fiat washer surrounding said pin and locatedy between said faces, one of said faces being so formed thatV only the periphery of said Washer bears thereagainst, the other points of saidwasher being spaced from said face, resilient means cooperating with said hinge pin tending to urge said faces toward each other, and the other ,of said faces having projections bearing one of. sai'd projections being adjustable.

3. A pivoted-leg instrument comprising a pair of legs having similar circular disc-like contiguous faces formed at their upper ends, a hinge pin extending through and joining said legs in a position substantially centrally of said faces,l a thin flat washer surrounding said' pin and located -between said faces. one ofsaid faces being so formed that only the periphery of said Washer bears thereagainst, the other points of said washer being spaced. from said face, resilient means cooperating with said hinge pin tending to urge said faces. toward each other, and the other of said faces having three spaced` projections bearing against said washer, one of said projections'being adjustable. Y

4. A drafting instrument or the like comprising a pair of legs. having. similar circular disclike contiguous faces formedat their upper ends, one. of said faces beingy slightly concave, a hinge pin extending through and joining said legs in a position substantially centrally of said' faces, a thin flat Washer surrounding said pin. and lo.- cated between said faces andbearing against said concave face at its periphery, said washer being spaced from said concave. face at *points other than its periphery lby reason, of the concave nature of said face, the otherofv said faceshaving spaced points-bearing against said washer, means to prevent relative rotation between the last said relatively movable elements being slightly con- 10 cave, the other of the contiguous faces having three projections substantially located at the apexes of an equilateral triangle, one of said projections being adjustable as to length, a thin at Washer located between said faces substantially coaxial with said pivot pin, and means to prevent relative rotation between said Washer and the face having the projections.

J AMES NASH.

CERTIF ICATE 0F C ORREGTION Patent No. 2,56Lb8o6. December 12, 19141;.

JAMES NASH.

or appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line lli, for "highly" read -slig,ht1y; and that the said Letters Patent should be read with this Correction therein that the same may cono the recordof the oase in the Patent Office.

It is hereby certified that err form t signed and sealed this 15th day of May, A. D. 1%5.

Leslie Frazer' (Seal) Acting Commissioner of Patents. 

